JPH05169447A - Method for regenerating polyurethane foam - Google Patents

Abstract

PURPOSE:To provide a method for regenerating high density, high strength foamed polyurethane molded products without causing the air pollution due to organic solvents used in adhesives because of the bonding of foamed polyurethane with adhesives in conventional methods being made unnecessary. CONSTITUTION:Particles of 3-8mm in size obtained by crushing thermosetting foamed polyurethane are preheated at 100-l80 deg.C for 5 minutes or more, and the thickness of the product is controlled with the land spacer of a mold so that the temperature in the mold is in a range of 190-210 deg.C and the density is 0.50-0.85/cc. In this way, the method for regenetrating foamed polyurethane by heating, compressing, and molding is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for recycling polyurethane foam, and more particularly to a method for obtaining a molded sheet of a foam by heating and compressing the polyurethane foam for recycling and recycling the polyurethane foam.

[0002]

2. Description of the Related Art Conventional methods for recycling polyurethane foam include, for example, the following methods. Defective products when molding polyurethane seat sheets, burrs on molded products, etc.
Alternatively, slab foam mill ends, burrs during foam molding, or defective polyurethane foam is crushed, and the resulting crushed product is sprayed with a polyurethane adhesive and heated with steam steam. A method is well known in which an adhesive is cured by gluing and a crushed product of urethane (which is called chip foam) is adhered and shaped in a mold. These waste urethane foams have a density of approximately
0.03 g / cc and the foam reused with adhesive has a density of about 0.06 g / cc. A method is also known in which RIM urethane used in bumpers is crushed and reused for a mudguard or the like using an adhesive. Further, the present inventor has made a polyurethane rubber fine powder in Japanese Patent Application No. 3-222398 to obtain a solid rubber-like elastic body having a density of 1.0 g / cc or more,
I proposed that this can be used for mudguards. Here, the density of 0.50-
We proposed a method to obtain a polyurethane molded product as a 0.85 g / cc foam.

[0003]

However, in such a conventional method for regenerating polyurethane foam,
Since urethane-based adhesives use organic solvents (such as methylene chloride), when heat-curing with steam, the organic solvent volatilizes into the air, causing air pollution or using adhesives. There is a problem that it is difficult to control the density of the regenerated foam due to the necessity of a process and the steam heat curing.

[0004]

The present invention has been made by paying attention to such a conventional problem, and polyurethane powder is crushed to obtain a powder having a particle size of 3 mm to 8 mm.
Preheat at 00 ~ 180 ℃, heat at 190 ℃ ~ 210 ℃, charge a predetermined amount in the mold, control the thickness of the molded sheet by the land height of the mold to control the density of 0.50 ~ 0.85 g / cc. The polyurethane foam can be regenerated by obtaining a molded product. That is, the method for recycling a polyurethane foam of the present invention is obtained by crushing a thermosetting polyurethane foam and then crushing the thermosetting polyurethane foam in the method for recycling a polyurethane foam in which a molded article is obtained by heating and compressing. 100 powder with a particle size of 3 to 8 mm
~ 180 ℃, preferably 170 ℃, 5 minutes or more, preferably 20 minutes preheat, mold in the temperature range of 190 ~ 210 ℃,
It is characterized by performing heat molding by controlling the thickness of the molded product by the land spacer of the mold so that the density becomes 0.50 to 0.85 g / cc.

[0005]

EXAMPLES The present invention will be described below with reference to examples. Example 1 End material of slab foam for construction, or urethane waste material in a factory or polyurethane foam used for a seat cushion or seat back of a scrap car is removed from the car, a vinyl cover and the like are removed, and a headrest is removed, Next, the urethane foam of the seat cushion and seat back was cut into a size of about 10 cm square with a band saw.

Next, the cloth, the reinforcing portion, and the reinforcing metal were removed, and coarse crushing was carried out by an ordinary crusher to a diameter of 5 mm to 8 mm.
The ground product was then dried in an oven at 170 ° C for about 20 minutes and preheated. Next, heat the mold to 190-200 ℃ in advance, fill the crushed product in the mold, apply pressure, pressurize until it contacts the land spacer of the mold, and heat for about 5 minutes. Thus, a molded product was obtained.

Depending on the weight of the crushed product filled in the mold and the height of the land spacer of the mold, the density of the molded product is 0.50 to
It is possible to change it to 0.85 g / cc, but if the filling amount of crushed molding raw material is reduced in the molding die and a flat plate of a certain thickness is molded, the specific gravity will decrease, but Since the internal pressure of the resin also becomes small, the surfaces of the powder particles are insufficiently heat-sealed to reduce the strength. With this hot press molding method, the density
If it is less than 0.5, it cannot be said that the practical strength is sufficient.
When it is higher than 0.85 g / cc, the molded product has a partially transparent portion. Here, the heat fusion property of the urethane foam will be explained as follows. The urethane bond is 190
It is known in principle to develop thermoplastic properties by dissociation at around ℃ (SAE 910581
Recycling of RIM scrapby Compression Molding).

The present invention was made based on this chemical principle. Dissociation of urethane bonds is shown by the following reaction scheme:

[Chemical 1]

Example 2 In this example, a molded product was obtained in the same manner as in Example 1 except that the particle size of the polyurethane foam powder was changed. When the particle size of the powder is about 1 mm, about 5 mm and about 10 mm, the density is
It was molded to 0.75 g / cc and tensile strength and elongation were measured. The obtained results are shown in Table 1. When the particle size was about 5 mm, both strength and elongation were large. If the particle size is about 10 mm, filling will be defective,
The molded product had unevenness in density and defects, resulting in poor surface smoothness and reduced strength.

The particle size is about 5 mm and the density is from 0.5 g / cc to 0.8 g / cc.
When it is changed to cc, as shown in Table 2, both the tensile strength and the elongation show larger values as the density increases, and the density 0.85 g / c
Above c, there are more transparent areas and the foam properties are lost. There are two types of polyurethane foam: HRF (high resilience foam) type, which is mainly used on the cushion side and has excellent elastic recovery, and HOT (hot mold) type, which is mainly used on the seat back (backrest) side. Table 3 shows the results obtained by comparing the two at a density of 0.75 g / cc. From these results, it is found that the strength is the same and the elongation of HRF is larger.

[0011]

[Table 1]

[0012]

[Table 2]

[0013]

[Table 3]

Under preheating conditions during molding, without preheating, the water content in the polyurethane foam evaporates into the mold during molding, and the strength of the molded product decreases. With a preheat temperature of 170 ° C,
Preheating time is 5 minutes, 10 minutes, 20 minutes, 30 minutes as shown in Table 4.
20 minutes gave the best physical properties. If it is longer than 20 minutes, the productivity will be low and the physical properties will not be improved.
When the preheating temperature was higher than 180 ° C., the urethane changed to yellow, indicating oxidative deterioration, and as shown in Table 5, both tensile strength and elongation decreased. 170 ° C is the desired preheat temperature.

Next, regarding the molding temperature, as shown in Table 6, when the conditions of 190 ° C., 200 ° C. and 220 ° C. are changed, it is 20
The best physical properties were obtained at 0 ° C.

[0016]

[Table 4]

[0017]

[Table 5]

[0018]

[Table 6]

[0019]

As described above, according to the present invention, the polyurethane foam is crushed and preheated at a temperature of 100 to 180 ° C. for 5 minutes or more with a particle size of about 3 to 8 mm, and the mold temperature is 190. As a method of obtaining a molded article of a foam by controlling the density by charging a predetermined amount at ~ 210 ° C, using a spacer of a certain thickness, and controlling the density, a crushed product of polyurethane foam is used as an adhesive. It eliminates the need for adhesion, prevents air pollution due to atmospheric emission of organic solvents that dissolve the adhesive, and controls the density of foamed molded products arbitrarily, resulting in higher density compared to conventional urethane foam cycle products. The advantage is that a polyurethane foam having high strength and novelty can be obtained.

Polyurethane foam moldings are excellent in elastic recovery, but they are not used frequently because the raw materials are expensive. However, since the raw material cost can be greatly reduced by the recycled products, it can be adhered to the carpet cloth to make the floor. Available as a mat. This floor mat is soundproof, vibrationproof and heat insulating. It can also be used as a dash insulator and has a soundproof effect.

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Claims (1)

[Claims] 1. A method for recycling a polyurethane foam, wherein a thermosetting polyurethane foam is crushed and then heated and compressed to obtain a molded article. A powder having a particle diameter of 3 mm to 8 mm obtained by crushing the thermosetting polyurethane foam. The 1
Preheat at a temperature of 00-180 ℃ for 5 minutes or more,
A method for regenerating polyurethane foam characterized by heating, compressing and molding by controlling the thickness of the molded product by the land spacer of the mold so that the temperature and density in the range of 0 ° C are 0.50 to 0.85 g / cc. ..